Download switched reluctance motor

SWITCHED RELUCTANCE
MOTOR
INTRODUCTION
Its is a type of stepper motor that works on
reluctance torque.
What is reluctance torque?
Control
 synchronizing the energy
 Positive torque (motoring)
 Negative torque (braking)
 Performance of SRM
 Electrical position sensor
Construction
Rotor
 Salient poles
 ferromagnetic material
 No windings
 Not physically connected to stator
Stator
 Salient poles
 Wound field winding
 2 wires per phase
 Connected to controller
Construction
 It is doubly salient and singley excited motor.
 Minimum reluctance positioning rotor.
 No. of pole in stator > no. of poles in rotor.
working
 The drive rotates the magnetic field.
 sequentially switching the current .
 rotating stator field induces a voltage .
 speed of the switched reluctance rotor .
 speed and the torque are controllable .
 Rotor is chasing current.
Power circuitry
Torque vs. Speed
• Operation is
programmable.
• Limitations
• Base speed
Applications
 Fault tolerance:
The motor circuit design has no short circuit paths across a dc power supply
in case of failure. The motor can run and even start with a fail condition
provided sufficient torque remains.
 Efficiency:
SRM efficiency can be maintained through a wide torque and speed
range.
BLDC motors have higher efficiency at low speed , SR motors have high
efficiency at high speed.
Applications
 Coal shearing
 Friction welding
 Textile spinning
Advantages
 Winding only on stator
 Rotor is smallest and has lowest
moment of inertia hence large
acceleration rate.
 Superior from maintenance point.
 Negligible rotor losses.
 Negligible mutual coupling.
Disadvantages
 Ripple torque is high but can be reduce by overlapping the phase current.
 F&W losses are high.
 Power converter to run.
 Position information is required.